The present invention relates to the use of beta-acids as extracted from hops for controlling Listeria and other food pathogens in food products intended for human consumption.
Recent studies have revealed that listeriosis in humans as caused by Listeria species and particularly Listeria monocytogenes is associated with the consumption of various types of foods, particularly soft cheese and pate as well as hams and other prepacked meat and poultry products. "Listeria Monocytogenes in Prepacked Ready-To-Eat Sliced Meats", a survey by the 16 public health laboratories in the PHLS food chain, by S. Velani and R. J. Gilbert, PHLS Microbiology Digest Vol. 7 (1990).
Hops and their associated acids have long been recognized as bacteriological inhibitors. More specifically, hop acids and resins have been shown to be primarily active against gram positive bacteria, e.g., Bacilli, Corynebacteria, Diplococci, Mycobacteria, Streptococci, Lactobacilli and Streptomyces. Most of the publications have focused on Lactobacilli, since this organism is a major contaminant in beer fermentation. Activity against gram negative bacteria is far less pronounced. Teuber and Schmalrek (Arch. Mikrobiol. 94, pp. 159-171, 1973) and Simpson and Hammond (European Brewery Convention, 1991) have suggested that the effect was due to induced permeability of the cell membrane in gram positive bacteria, but was inactivated by serumphosphatides in gram negative bacteria.